This invention relates to novel chemical compounds and to their preparation, and more particularly to 7,7,8,8-tetracyanoquinodimethane (hereafter referred to simply as TCNQ) compounds and method for the preparation of such compounds.
Recently integrated circuit technologies have remarkably progressed in the electronics field, and very large scale integrated circuits (VLSI) have been realized. However, the present technology for miniaturizing the integrated circuit is near the limit, and different approaches are required. For this purpose, various research of molecular electronics has been conducted.
Under the circumstances, the inventors thought that it was necessary to provide an organic compound which has electronic conductivity substantially equal to metals, and the molecules of which can be arranged in regular fashion. There are at present no organic compounds which have these characteristics.
Organic compounds, the conductivity of which are substantially equal to metals, are known such as a complex compound of TCNQ and tetrathiofulvalene (hereafter referred to as TTF). The complex compound is expressed by the following formula: ##STR1##
TCNQ and TTF form a charge-transfer complex because TCNQ is a strong electron acceptor and TTF is an electron donor. The complex has electric conductivity the maximum value of which is comparable with the electric conductivity of mercury. However, the complex of TTF and TCNQ has not been manufactured or processed in a monomolecular layer. Langmuir-Blodgett's technique is generally known in the art as a technique for arranging molecules in a monomolecular layer. However, generally known TCNQ derivatives cannot be processed in a monomolecular layer or film by the Langmuir-Blodgett technique.
Meanwhile, many studies have been directed to synthesize TCNQ derivatives. U.S. Pat. No. 3,558,671 discloses a method for synthesizing TCNQ fluoride and cyano TCNQ, in which quaternary ammonium salt is synthesized for use as dyestuff or pigment. U.S. Pat. No. 3,739,008 discloses a different method for synthesizing TCNQ fluoride and cyano TCNQ for use as dyestuff or antistatic agent. U.S. Pat. No. 3,687,987 discloses a method for synthesizing dialkoxyl TCNQ containing up to 8 carbons in the alkoxy groups. U.S. Pat. No. 3,526,497 discloses a method for synthesizing dialkoxyl TCNQ and dialkoxyl TCNQ fluoride, where the alkoxy groups contain up to 13 carbon atoms. U.S. Pat. No. 3,115,506 discloses a synthesizing method of TCNQ having an alkyl group of up to 8 carbons from alkyl substituted 1,4-cyclohexane-dione.
A method for synthesizing TCNQ having an alkyl group of up to 3 carbons is discussed in Journal of Organic Chemistry, vol. 28, p. 2719, 1963, in which 2-methyl-1,4-dimethoxybenzene obtained from 2-methylhydroquinone is reduced.
However, these synthesizing methods are unsuitable for a novel TCNQ product having higher alkyl group, because of small yield.